tireheight.com

185/55R15 in inches

A 185/55R15 tire is 23.0″ tall and 7.3″ wide, and fits a 15″ wheel. In inches it is written 23.0×7.3R15.

Diameter23.01″
Width7.28″
Sidewall4.01″
185/55R15 drawn to scale: 23.01 inch diameter, 4.01 inch sidewall, 15 inch wheel, 7.28 inch tread width15″ wheel4.01″23.01″ overall7.28″ wideSide view
Drawn to scale. Nominal dimensions calculated from the size code.
Manufacturer data

How tall 185/55R15 tires really are

Heights published by General and Toyo for all 4 tires in this size. Their published revolutions per mile work out to 22.3–22.4″ under load (below).

Real 185/55R15 tires measure 23.00–23.03″, against 23.01″ from the size code. They run both taller and shorter than the size code.

Height under load22.3–22.4″

Published revs per mile (902–903) mean the tire rolls like a 22.3–22.4″ tire on the vehicle. Use this for speedometer calibration.

Weight spread15.6–18.1 lb

The lightest (General AltiMAX RT45, SL) is 2.5 lb lighter per corner than the heaviest (Toyo Observe G3-Ice, SL).

4 tires in 185/55R15

Sort by the spec you care about.

LoadRevs/miSource
General AltiMAX RT45TouringSL · 82V23.0015.611.01,047903Spec page
General AltiMAX RT45TouringSL · 82H23.0015.911.01,047903Spec page
General AltiMAX365 AWTouringSL · 82H23.0015.911.01,047903Spec page
Toyo Observe G3-IceWinterSL · 82T23.0318.111.31,047902Spec page

Is 185/55R15 a 23-inch tire?

≈23″

Yes. The size code works out to 23.01″, and the 4 tires here publish 23.00–23.03″, so people call it a 23.

Compare with nearby sizes

Differences in overall diameter, calculated from each size code.

SizeDiameter ″vs 185/55R15Difference
195/50R1522.68-0.33″-1.5%
245/40R1522.72-0.30″-1.3%
195/45R1622.91-0.10″-0.4%
175/65R1422.96-0.06″-0.2%
225/45R1522.97-0.04″-0.2%
205/50R1523.07+0.06″+0.3%
195/55R1523.44+0.43″+1.9%
185/60R1523.74+0.73″+3.2%
225/50R1523.86+0.85″+3.7%
175/65R1523.96+0.94″+4.1%

How to read 185/55R15

How to read any tire size

185/55R15 82H as printed on the tire sidewall, with each part numbered185/55R15 82H123456
How 185/55R15 82H is printed on the sidewall. It's the most common code among the 4 tires here (2 of them); tires in this size come in other load and speed ratings too.
1185Section width

185 mm across the widest point, or 7.28 inches. Every 185 size

255Aspect ratio

A percentage, not a measurement: the sidewall is 55% as tall as the tire is wide, which is 101.8 mm or 4.01 inches.

3RConstruction

Radial construction.

415Wheel diameter

Mounts on a 15-inch wheel. Approved wheel widths run 5.0″ to 6.5″.

582Load index

Each tire carries up to 1,047 lb (475 kg) at its maximum pressure.

6HSpeed rating

Rated for up to 130 mph sustained.

SpecificationInchesMetric
Overall diameter23.01585 mm
Section width7.28185 mm
Sidewall height4.01101.8 mm
Circumference72.31,836 mm
Revolutions per mile (calculated, unloaded)876.4545 per km
Revolutions per mile (published by manufacturers)902–903560–561 per km
Approved wheel width5.0–6.5127–165 mm

Speedometer error after switching to 185/55R15

Your actual speed– mph

Questions about 185/55R15

What is 185/55R15 in inches?

23.01 inches tall, 7.28 inches wide, on a 15-inch wheel. Written in inches, that is roughly 23.0×7.3R15.

How much does a 185/55R15 tire weigh?

Between 15.6 lb and 18.1 lb for the 4 tires listed here. The lightest is the General AltiMAX RT45 (SL); the heaviest is the Toyo Observe G3-Ice (SL).

What wheel width do I need for 185/55R15?

Manufacturers approve 5.0–6.5″ wide wheels for this size.

How many revolutions per mile does a 185/55R15 make?

Published figures run 902–903 revolutions per mile. The calculated figure is 876.4, but manufacturers measure the tire under load, where it rolls on a smaller radius.

How much taller is 185/55R15 than 225/45R15?

0.04 inches taller on paper (23.01″ vs 22.97″), which raises the axle about 0.02″. Your speedometer will read about 0.2% slow.